The effects of smoking on birthweight-for-gestational-age curves in teenage and adult primigravidae

Abstract

Objectives. To compare the effect of smoking on the birthweight-for-gestational-age curves of teenage and adult primigravidae. Methods. A retrospective analysis of the perinatal database at the Liverpool Women's Hospital for the years 1997–1999 for teenage and adult primigravidae. Results. Records on 1157 primigravidae were available. There were no significant differences between the mean birthweight (3220 g±666 vs 3244 g±680, P=0.43) and the proportion with low birthweight (LBW) babies (8.9% vs 10.6%, P=0.39) between teenage and adult primigravidae, respectively. The percentage of women who smoked increased from the middle class (Townsend score −6–−3) to the working class group (Townsend score +4–+12) for both teenagers (33.3–51.3%) and adults (6.9–29.6%). The mean birthweight of babies of smoking mothers was significantly lower than for non-smoking mothers (3112 g±639 vs 3327 g±663, P=0.00002). The birthweight-for-gestational-age pattern was lower at all gestational ages for smoking mothers in both the teenage and adult groups. Risk of LBW was significantly increased in teenagers who smoked (10.8% vs 3.9%, P<0.01), but not in adult smokers. Conclusion. Lower birthweights at all gestational ages were observed in babies of teenage and adult mothers who smoked.